Rotary shaft air-tightly fitting device

ABSTRACT

This invention relates to a device for air-tightly fitting a rotary shaft, for example, for an anode in a rotary opposite cathode X-ray tube whereby it is made possible to remarkably elongate the life of each packing by reducing the wear of the packing without causing a leakage by reducing the pressing contact force of the packing with a centrifugal force.

0 United States Patent 1191 1111 3,778,070 Shimura 1 Dec. 11, 1973ROTARY SHAFT AIR-TIGHTLY FITTING 3,565,447 2 1971 Goetze 277/59 DEVICE3,622,164 11/1971 Herbert 277/l34 [75] Inventor: Yoshihiro Shimura,Nakano-ku,

Tokyo, Japan Primary ExammerHerbert F. Ross Asslgnee! Rigak" Dank p yAssistant ExaminerRobert l. Smith Tokyo, Japan Attorney-Alfred W.Breiner [22] Filed: Feb. 24, 1972 [21] Appl. No.2 228,923

57 ABSTRACT [30] Foreign Application Priority Data 1 Aug. 3], 1971 Japan46/663 14 This inventlon relates to a dev1ce for alr-tlghtly fitting1521 11.8. c1. 277/58 277/134 rotary Shaft, example a Mary 511 1111. C1F16j 15/16 caflwde x'ray tube whereby it is made Possi' [58] Field 6:Search 277/25 58 59 61 Me remarkably the each Packing by 277/62 reducingthe wear of the packing without causing a leakage by reducing thepressing contact force of the [56] References Cited packing with acentrifugal force.

UNlTED STATES PATENTS 1,354,192 9/1920 Howe 277/134 1 Claim, 2 DrawingFigures PATENTEDUEC 1 1 I973 FIG.-

FIG.2

ROTARY SHAFT AIR-TIGI-ITLY FITTING DEVICE This invention relates to anair-tightness holding device for fitting and passing a rotary shaft, forexample, for an anode in a rotary opposite cathode X-ray tube through anair-tight wall so as to be connected with an outside driving source.

In such device, an oil low in the viscosity is contained between twoannular packings through which is fitted and passed a rotary shaft and aspiral concave groove is made on the shaft.

An object of the present invention is to provide such device forair-tightly fitting a rotary shaft whereby the wear of each packing in ashaft-sealing device is reduced as is mentioned above.

In the drawing;

FIG. 1 is a vertically sectioned view of an embodiment of a deviceaccording to the present invention;

FIG. 2 is a partly magnified view of FIG. 1.

FIG. 1 is a vertically sectioned view of an embodiment of the presentinvention as applied to a rotary opposite cathode X-ray tube and FIG. 2is a magnified view of a part of FIG. 1. An air-tight chamber 3containing a cylindrical rotary anode l and an electron radiatingcathode 2 provided opposite a part of the pe-- ripheral side surface ofthe anode l is connected to a high vacuum exhaust pump. A cylindricalbearing part 5 is formed in an air-tight wall 4 in this air-tightchamber 3 and a rotary shaft 6 of the above mentioned anode l is fittedand passed through said bearing part 5 and has a pulley 7 fixed to itsfree end. That is to say, the pulley 7 is connected with an electricmotor so as to rotate the anode l at a high speed. The shaft 6 is heldby ball bearings 8 and 9 arranged at both ends of the above mentionedcylindrical bearing part5. Therefore, when electron rays are projectedfrom the cathode 2 onto the peripheral side surface of the anode l,X-rays will be generated from said anode. In such X-ray tube,

two annular packings l0 and 11 formed of rubber or the like are fixedbetween the bearings 8 and 9 on the rotary shaft 6 and are opposedrespectively to the atmosphere and the air-tight chamber 3 by pressingflanges made by projecting the outside surfaces of the annular packingsl0 and 11 toward the inside of the cylindrical bearing part 5 intocontact with a part of the airtight wall 4. Further,a cylindrical body12 closely fitted to the inside surface of the cylindrical bearing part5or therefore to the air-tightwall 4 is provided between the abovementioned two packings l0 and 11, is fixed to the shaft 6 and has aspiral concave groove 13 formed on the peripheral surface. That is tosay, as a cylindrical sealed chamber is formed between the packings l0and 11 arranged in both end parts of the above-mentioned spiral concavegroove 13, this sealed chamber is filled with an oil 14 low in theviscosity and vapor pressure and the oil between the packing l0 opposedto the atmosphere on the pulley side and the spiand the above mentionedspiral groove 13 will be sucked out into the oil tank 16 and will beequilibrated while the end of the oil is in a proper position in thegroove 13 so that the oil chamber between the above mentioned packingand the spiral groove 13 may be vacuum. As the packing 11 is fixed tothe shaft 6, it will rotate at a high speed together with this shaft.Therefore, such centrifugal force as is shown by the arrow r in FIG. 2will act on the above mentioned packing 11 and, by a component of thiscentrifugal force, said packing will be separated from the air-tightwall or its pressing contact force will be remarkably reduced. F urther,even in case the force applied to the oil by the spiral groove 13 issmaller than 1 atmosphere, the oil pressure between said spiral groove13 and packing 11 will become lower than 1 atmosphere correspondingly tothe above mentioned force. At the same time, the force with which thepacking 11 is pressed into contact with the air-tight wall will bereduced by the centrifugal force. That is to say, in case the shaft 6 isstopped, an oil pressure of 1 atmosphere will be applied between thepacking 11 and spiral groove 13 and the above mentioned packing will bepressed into contact with the air-tight wall with a strong force toprevent the oil from leaking into the air-tight chamber. When the shaft6 rotates, the above mentioned oil pressure will reduce and, at the sametime, the pressing contact force of the packing will be reduced by thecentrifugal force. Therefore, there will be no fear of the oil leakinginto the air-tight chamber, the friction between the packing andair-tight wall will reduce, therefore the wear of the packing will beremarkably reduced and its life will elongate. By the way, the packingl0 opposed to the atmosphere has no pressure difference between theinside and outside of it and therefore may well be in contact with theair-tight wall so lightly as to prevent the flow of the oil under itsown weight. Therefore, this packing 10 may be provided, for example,with a metallic core to prevent the action of a centrifugal force andmay be-in contact with the air-tight wall always under a substantiallyconstant small pressure so that the wear may be prevented. Further, asthe space between the rotary shaft 6 and air-tight wall 4 is alwaysfilled at least partly with an oil low in the viscosity, theair-tightness can be perfectly held.

As described above, in the device of the present invention, annularpackings are fitted to a rotary shaft and are pressed into contact withan air-tight wall and a spiral concave groove is made on said rotaryshaft and is closely fitted to the air-tight wall. Therefore, with thepumping action of the above mentioned spiral groove, the packing partcan be made vacuum or at least the oil pressure in said part can bereduced, further, with the centrifugal force, the pressing contact forceof the packing can be reduced and thus, without producing a leakage, thewear of the packing can be reduced and its life can be elongated.

What is claimed is:

l. A rotary shaft air-tightly fitting device which comprises anair-tight wall, a rotary shaft closely fitted and passed through saidair-tight wall, a spiral concave groove made on the peripheral sidesurface of said rotary shaft in the passing part of the rotary shaft andtwo annular packings arranged respectively at boty ends of said spiralconcave groove and opposed on the outsides respectively to theatmosphere and the air-tight chamber, said first annular packing opposedto the above mentioned air-tight chamber being fixed to the abovementioned rotary shaft and pressed on the outside surthe oil betweensaid second annular packing opposed face into contact with the abovementioned air-tight to the atmosphere and the above mentioned spiralconwall, the space between the above mentioned two cave groove beingconnected with the atmosphere. packings being filled with an oil low inthe viscosity and

1. A rotary shaft air-tightly fitting device which comprises anair-tight wall, a rotary shaft closely fitted and passed through saidair-tight wall, a spiral concave groove made on the peripheral sidesurface of said rotary shaft in the passing part of the rotary shaft andtwo annular packings arranged respectively at boty ends of said spiralconcave groove and opposed on the outsides respectively to theatmosphere and the air-tight chamber, said first annular packing opposedto the above mentioned air-tight chamber being fixed to the abovementioned rotary shaft and pressed on the outside surface into contactwith the above mentioned air-tight wall, the space between the abovementioned Two packings being filled with an oil low in the viscosity andthe oil between said second annular packing opposed to the atmosphereand the above mentioned spiral concave groove being connected with theatmosphere.